Activation of JNK/SAPK in primary glial cultures: II. Differential activation of kinase isoforms corresponds to their differential expression.
Recently, we reported on the activation of c-Jun N-terminal kinase (JNK) in primary glial cells noting certain differences in the patterns of kinase activation in astrocytes and oligodendrocytes (Zhang et al., J Neurosci Res 46:114-121;1996). In this extended study, we have examined the activation and expression levels of JNK1 and JNK2 isoforms in different glial cell types including the two in vitro-defined astroglial subtypes (type-1 and type-2), oligodendrocytes and microglia. An in-gel kinase assay of cell extracts and JNK-immunoprecipitates revealed the activation of both JNK1 and JNK2 in type-1 astrocytes in response to TNFalpha, and in microglia, in response to TNFalpha and bacterial lipopolysaccharide. The strong activation of the two JNK isoforms in type-1 astrocytes and microglia contrasted with a predominant activation of JNK1 over JNK2 in type-2 astrocytes and oligodendrocytes, the two glial subtypes sharing a common lineage. Immunoblot and immunocytochemical analyses using isoform-specific antibodies showed a differential expression of the two isoforms in different glial cells thereby accounting for their observed differential activation.
Zhang
P
P
Department of Neurology, Medical University of South Carolina, Charleston 29425, USA.
Hogan
E L
EL
Bhat
N R
NR
D000818:Animals; D000831:Animals, Newborn; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000096:biosynthesis* / Q000378:metabolism*; D002478:Cells, Cultured; D004789:Enzyme Activation / Q000187:drug effects; D007527:Isoenzymes / Q000096:biosynthesis* / Q000378:metabolism*; D048031:JNK Mitogen-Activated Protein Kinases; D008070:Lipopolysaccharides / Q000494:pharmacology; D048056:Mitogen-Activated Protein Kinase 9; D020928:Mitogen-Activated Protein Kinases; D009457:Neuroglia / Q000187:drug effects / Q000201:enzymology*; D011494:Protein Kinases / Q000096:biosynthesis* / Q000378:metabolism*; D051381:Rats; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology
D007527:Isoenzymes; D008070:Lipopolysaccharides; D014409:Tumor Necrosis Factor-alpha; D011494:Protein Kinases; D048056:Mitogen-Activated Protein Kinase 9; D017871:Calcium-Calmodulin-Dependent Protein Kinases; D048031:JNK Mitogen-Activated Protein Kinases; D020928:Mitogen-Activated Protein Kinases